Using pipe relining to rehab a hospital's drainpipe system
Eaves-dropping from the VA’s attics.
The project planning team of the Veterans Affairs Hudson Valley Health Care System couldn’t find a plumbing contractor who could meet the unique specifications of the drainpipe rehabilitation job at its historic Franklin Delano Roosevelt Campus in Montrose, N.Y., which provides tertiary care in acute and chronic psychiatry. The roof drainage system of the 30 office-style buildings — gutter drains with 40-ft. to 50-ft. vertical drops of 3-in. cast-iron pipe — was completely concealed within the walls of its appealing architecture and exterior brick veneers during initial construction.
In crawl spaces beneath the buildings, the drains made a 90° transition to 4-in. horizontal pipe in concrete slab-on-grade to lead rain water to the storm sewer system. Neither interior wall demolition to access the pipe nor exterior modification to reroute them were satisfactory options, so the chosen rehabilitation method was vertical cured-in-place-pipe technique.
In late 2013, Tribal Construction Corp., the general contractor for the job, turned to Whispering Pines Development Corp. of Vails Gate, N.Y., for the CIPP installation. The technique basically creates a new and improved drainage system from the existing one — without jeopardizing the aesthetics of the campus architecture or disrupting the hospital’s sensitive operations.
Shortened learning curve
The manufacturer of the equipment and consumables was HammerHead Trenchless Technologies. Ryan Boldan, HammerHead lateral product manager, says about half of his new CIPP clients are plumbers or lateral cleaning specialists. They either know CIPP installation techniques already and want to avoid having to sub it out or are looking to expand the services they can offer their customers.
Some clients, however, are completely unfamiliar with CIPP technology. They are investigating its potential and need to learn the installation technique from scratch. “It’s not hard to learn,” Boldan notes. “Most will find that it’s a straightforward process and master it fairly quickly.”
HammerHead CIPP technician Cory Steckmannserves as technical consultant for matching a product combination to a specific project’s requirements. For the VA project, he not only took the project owner’s specifications into account but also advised the contractor of potential installation difficulties on the job — such as a vertical run three stories high would affect liner curing requirements and liner stretch due to gravity — saving the contractor from the frustration and expense of learning through trial and error.
Steckmann also recommended a resin that would cure under the ambient temperatures of this particular jobsite rather than exposing the walls to the heat of a steam-curing process.
“The package for this project also included training,” he notes. “We helped the contractor get started and were there to oversee things as the crew got familiar with the equipment and process.”
The contractor’s six trainees were running lines on their own in short time on the first building. From that point forward, installation was performed by a four-man crew. The two additional trainees stood in as needed during the months of installation that followed.
Each building required renovation of 20 to 22 cast-iron drainpipes. Equipment and materials included two HammerHead Mini-Hydra CIPP lining inversion drums, four application nozzles, four 150-psi portable air tanks, Picote chain flails for cleaning the existing pipes, a Picote CIPP reinstatement system and more than 7,100 ft. each of composite liner and calibration tubing, with epoxy resin and hardener.
The liner is 3-in. and 4-in. HammerHead HH Flex Liner, which is designed for multiple bends with minimal wrinkling. It can be used in pipe with up to 90° bends and in pipe-size transitions. Once cured, it will retain its integrity and stiffness to soundly bridge irregularities, gaps or splits in the existing pipe without bulges or failures. The felt tubing’s material composition was matched to the installation pressures as well as the resin and hardener curing temperatures specified for this application.
First the crew opened an access into an existing vertical pipe at the elbow where it met the gutters inside the attic. Then they cleaned the pipe of tuberculation with powered chain flails.
Steckmann says cleaning was a remarkably quiet operation, since the flails are sized for the pipe and “really just scour or grind rather than flail.” The only audible sound was a muted scraping within the office walls. Video camera inspections after cleaning verified installation readiness.
The crew cut felt tubing to length for the wet-out process. Wet out begins by clamping a liner at one end, then using a pump to create a vacuum within the liner. The crew poured resin in through the open end, sending it through adjustable rollers mounted on the wet-out table to completely and uniformly impregnate every fiber of the liner.
When the wet-out process was complete, the team spooled the liner onto the reel of an inversion drum. Then they folded the tail end over the inversion drum’s nozzle like a cuff and clamped it in place. Placing the nozzle against the pipe opening, they charged the drum with compressed air. Under pressure, the liner inverted wet-side-out as it exited the drum into the existing pipe.
After the inversion process, the crew disconnected the nozzle to spool an inflatable hose called a calibration tube onto the drum’s reel. They inverted the calibration tube into the installed liner. Pressurizing the calibration tube to 10 psi pushed the liner uniformly against the pipe throughout its full length. Some product combinations call for water or steam for this step. Air at ambient temperature was specified for this project.
After a five-hour cure time, the crew removed the nozzle and withdrew the calibration tube from the pipe. They verified the quality of the clean, new, joint-free pipe with a video camera before reconnecting it to return it to service.
Not all attics offered adequate space to lay out the lengths of liner for measurement and wet out. “We did the wet outs outside and then carried the loaded drums up several stories,” says John Leonette, owner of Whispering Pines. “Once in the attics, there were trusses and obstructions on the floor we had to navigate to get it all in place.”
The crew performed wet out and inversion for four runs each morning. It took about an hour per 50-ft. run to prep the pipe, install liner and set up a portable air tank to maintain pressure throughout the cure time. In the afternoon, the crew removed calibration tubes, video-inspected the installations and reconnected the four drainpipes.